Summary

The incidence of cancer was studied in a cohort of patients, comprising 1148 males and 2764 females, who had undergone a cholecystectomy in Geneva during the period 1973 to 1980. They were observed up to the end of 1982 or as long as they resided in Geneva, and the material totalled 21,004 person/years of observation. It is estimated that more than 95% of the eligible individuals, operated upon during this period, were included in the study.

Cases were followed up through the official population records, and incident cases of cancer were obtained by record linkage with the files of the Geneva Cancer Registry. Relative risks were estimated in relation to the incidence observed in the overall population during the period considered, adjusted for age; they were expressed in SMR's.

The first year of observation was excluded in order to eliminate those cases in which cholecystectomy was performed within the scope of cancer treatment surgery.

There was no increase in colorectal cancer nor in other sites. A slight increase was observed in the total number of cancers for females.

These results are similar to those obtained in most studies of the same kind. The absence of an increased risk after a longer period of observation cannot be excluded, since the average observation time does not exceed six years, and the analysis must be repeated after a few more years. The excess in total of cancer is probably due to better surveillance of cholecystectomized female patients.